Journal of Applied Sciences and Environmental Management World Bank assisted National Agricultural Research Project (NARP) - University of Port Harcourt ISSN: 1119-8362 Vol. 12, Num. 1, 2008, pp. 109-11

Amino Acid Profile of Biodegraded Brewers Spent Grains (BSG)

*Essien, J. P.; Udotong, I. R.

Department of Microbiology, University of Uyo, P.M.B. 1017, Uyo, Nigeria. *Corresponding Author: jomato652003@yahoo.com

Code Number: ja08016

ABSTRACT

The amino acids profiles of biodegraded brewers spent grains (BSG) were determined. The
analysis revealed the presence of 17 amino acids including the major amino acids (cysteine, lysine and
methionine) required in poultry nutrition. The concentrations of the amino acids however varied with the
microbial species used in the degradation process. After 10 days of solid state fermentation at room
temperature glusine, alanine and phenyalanine were detected at very high concentration in Aspergillus niger
TF-4 degraded BSG. Glusine, alanine and proline were the major amino acid components of BSG degraded
by Saccharomyces cerevisiae FP-4, while glusine, alanine and leucine were found to be the major components
of BSG degraded by Streptomyces sp UU-2. The concentrations of the required amino acids except lysine
were short of the standard requirement for poultry. However their concentrations were positively affected over time by biodegradation. @JASEM

In bioconversion of organic wastes, the protein constituent of the complex substrate is usually broken down into amino acids by the proteolytic activity of the degraders (Singh et al., 1988 and Barimalaa et al., 1994). Farm animals build their body protein primarily from the amino acids absorbed from the digested dietary protein (Sastry and Thomas 1976). In order to synthesize a particular protein all the amino acids required by the animal body must be simultaneously present in sufficient quantities. The body has the capacity to convert surplus of some of the simpler amino acids into certain others. On the other hand, the large animal tissues cannot form certain amino acids from any other source. The later groups of amino acids are called the essential amino acids (Ranjhan et al., 1974, Sastry and Thomas, 1980). The essential amino acids are necessary for life and must be supplied through feeds in required quantities (Portsmouth, 1978). Our preliminary investigation on the bioconversion of brewers spent grains (BSG) into poultry feed revealed a general increase in dietary protein of BSG degraded by Aspergillus niger TE-4, Saccharomyces cerevisiae FP-4 and Streptomyces sp-UU-2 over time (Essien et al., 2007). This study focuses on the qualitative and quantitative amino acids profile of the biodegraded spent grains.

MATERIALS AND METHODS

Sample Collection: Brewer’s spent grains (BSG) samples used in this study were collected from Golden Guinea Brewery PLC. Umuahia, Nigeria. The biodegraders, namely Aspergillus niger TE-4, Saccharomyces cerevisiae FP - 4 and Streptomyces sp. UU-2 were isolated from textile effluent, fresh palmwine and Uyo ultisol, respectively. The isolates were characterized and their identities confirmed according to the procedures described by Samson et al., (1984), Kreger-Van Rif (1984), Buchannan and Gibbons (1974) and Cowan (1985). The fungal isolates were purified and maintained on Sabouraud dextrose agar (Difco) plates, while pure cultures of the bacterium, Streptomyces sp. UU-2, was maintained on slightly acidic (pH 5.6) nutrient agar (Difco) plates. None of the biodegraders have been associated with poultry illnesses. Thirty (30) grams sample of the BSG were sterilized by autoclaving at 121°C and then degraded with 5 day old pure cultures of Aspergillus niger TF-4, Saccharomyces cerevisiae FP-4 and Streptomyces sp. UU-2. The modified solid state fermentation technique was adopted. In this procedure 30g of sterile BSG samples were aseptically transferred to sterile 500ml Erlenmeyer flasks, and inoculated separately with 10ml spores/cell (10⁶ spores/cells per ml) suspension obtained from 7 day old pure cultures of the test organisms. The inoculated flasks in replicates of three were allowed to ferment for 10 days at room temperature (28 + 2°C). A set of uninoculated flask containing 30g of sterile BSG served as the control. This technique has previously been used by Singh et al, (1988) and Barimalaa et al, (1994) for bioconversion of organic wastes.

Amino Acid Analysis: During the biodegradation
process, subsamples of 3 and 10 day old fermented
BSG samples were subjected to amino acid
analysis. About 50mg of the biodegraded BSG
samples were homogenized and hydrolysed with
10mI of 6N HCI containing 1% thioglycollic acid
under vacuum at 110°C for 24 hr. Prior to amino
acid analysis both the acid and alkaline
hydrolysates were neutralized. The solution of the
hydrolysates were injected into a Hitach 1835
automatic amino acid analyser and the amino acid
quality determined by ion-exchange
chromatography on a cationic exchange as
described by Glazer et al., (1976).

The amino acid mixtures were often taken up in an
acid buffer and loaded on the ion exchange column.
The more basic amino acids were most tightly
bound than those with acidic groups. The column
was eluted gradually into buffers of increasing pH
and ionic strength. The acidic amino acids were
removed readily from the resin followed by neutral amino acids and finally by basic amino acids. Each
amino acid was clearly separated from the other.
The individual amino acids were quantified by
reaction with ninhydrin and the resultant colour density was measured by spectrophotometry. The concentration of the amino acids was expressed in g/16gN (Glazer et al, 1976).

RESULTS AND DISCUSSION

The analysis revealed the presence of variable concentrations of lysine(Leu), histidine (His), arginine (Arg), asparagine (Asp), threonine (Thr), serine (Ser), glusine(Glu), proline (Pro), glycine (Gly) alanine (Ala), cysteine (Cys) valine (Val), methionine (Met), isoleucine (Ileu), Ieusine (Leu) tryptophan (Try) and phenylalanine (Phe) in biodegraded BSG (Table 1). Of all these amino acids the most important amino acids in poultry nutrition are cysteine, lysine and methionine (Portsmouth 1978, Ranjhan et al., 1974, Sastry and Thomas 1988). Other amino acids necessary in poultry feeds, also detected in the fermented BSG were histidine, arginine, asparagine, glycine, valine, isoleusine Ieusine, tryptophan and phenylalanine. But their concentrations were remarkably higher than the values recommended for poultry nutrition. The results also revealed that the concentrations of lysine, histidine, asparagine, threonine, proline, glycine, alanine, valine, methionine, isoleusine, leusine, tryptophan and phenylalanine decreased with increase in fermentation period while the concentrations of arginine, serine, glusine and cysteine increases with the fermentation period.

A summary of the amino acids composition
(g/16gN) also shows a reduction in the lysine level
of the spent grain from 2.17g to 1.10g/16N by
Aspergillus niger, to 1.16g /16gN by
Saccharomyces cerevisiae and to 1.54g/16gN by
Streptomyces sp within 10 days of fermentation at
room temperature. Same was observed for the
concentration of cysteine which was reduced from
its initial content of 0.74g/16N to 0.30g/16g/N by
A. niger, 0.36/16gN by S. cerevisiae and to
0.71g/16g/N by Streptomyces sp within 10 days.
Similarly, the concentration of methionine was
reduced from1.86g/16gN to 1.52g/16N,
1.25g/16gN and 1.83g/16gN respectively by A.
niger, S. cerevisiae and Streptomyces species.
Apart from the values obtained for lysine, the
concentrations of cysteine and methionine recorded
after 10 days of fermentation were short of the
requirement for poultry (Portsmouth 1978, Sastry
and Thomas 1980). The higher values recorded for
these amino acids after 3 days of degradation is an
indication that if the spent grains are fermented for
a longer period, the biodegraders would
successfully convert them to levels necessary for poultry. Other amino acids, namely, histine,
arginine, proline, glycine, valine, isoleusine,
tryptophan and phenylalanine were also positively
affected by the fermentation process but will
require a much longer period to be degraded to the
recommended standards for poultry nutrition. On
the other hand fermentation by S. cerevisiae and
Streptomyces had little effect on the concentrations
of threonine, serine, glucine, proline, alanine, and
leusine in BSG, although the biodegraders are of
high proteolytic potential.

REFERENCES

• Cowan, S T (1985). Cowan; Steel’s Manual for Identification of Medical Bacteria. 2^nd Edition. Cambridge University Press London.
• Essien, J P; Udotong, I R; Bassey, MP (2007) Bioconversion of brewers spent grains (BSG) for possible use as poultry feed Journal of Sustainable Tropical Agricultural Research (in press).
• Glazer, A M; Aelange, R G; Sigma, D S (1976). Chemical modification of protein. Laboratory Techniques in Biochemistry and Molecular Biology I, 200-206.
• Kreger-Van Rij, N J W (1984). The Yeast Taxonomic Study. 3^rd Edition Elsevier – North-Holland, Amsterdam.
• Portsmouth, J (1978). Nutrition Feeding. Practical Poultry Keeping. Saiga Publishing Co. Ltd. pp. 53-72.
• Ranjhan, S K., Sawhney, P C., Jayal. M M (1974). Characteristics of feeds and feed additives. In Animal Nutrition in the Tropics. Vikas publishing House PVT. Ltd pp. 159 –179.
• Samson, R A., Hoekstra, E S; Van Ooorschot, CAN (1984) Introduction to Foodborne Fungi. 2^nd Edition, Central Bureau Voor Schimmelcultures. Baaru. Holland.
• Sastry, N S R., Thomas, C K (1980). Feeding Farm Animals. In Farm Animal Management. Vikas Publishing House PVT Ltd, pp. 116 –300.
• Singh, A; Abidi, A B., Darmwal, N S; Agarwal, A K (1988). Bioconversion of Ligncellulosic residues for the production of protein and cellulose in solid state culture. Proceedings of Seminar on Application of Biotechnology for Agriculture and Rural Development, NIRD Hyderabab pp. 69 –78.

Copyright 2008 - Journal of Applied Science and Environmental Management

The following images related to this document are available:

Photo images